Development of a new kind low frequency low-noise vector sensor

A new kind low frequency low-noise vector sensor (VS) with minimum size by relaxor-based ferroelectric crystals had been presented. The VS is composed with a built-in accelerometer and a JFET-based preamplifier, which has significant contribution to the self-noise performance. Measured equivalent noise pressure level (ENPL) of the prototype is about 52.8, 44.2 and 31.9dB/root Hz at frequencies 100, 200 and 500 Hz, respectively. It is significantly lower than the ambient noise of Knudsen Sea state zero at frequency band 60 similar to 1000Hz. The obtained results exhibit a high level of consistency with the prediction by modelling the ENPL of VS. For decreasing the self-noise at low frequency, a cross-ring beam accelerometer using [011] cut relaxor-based ferroelectric crystal is proposed. Prototype has been fabricated and characterized. Measurements about performance of the prototype gives a sensitivity of -212.9dB@100Hz without amplification as well as a diploe directivity with null depth of -36.2dB, which is in good agreement with the finite element analysis. The designed prototype provides the possibility for practical applications of low frequency underwater sound detection. (C) 2019 Published by Elsevier B.V.